1. Field of the Invention
The present invention relates to an input device constituting an operation unit of various electronic apparatuses.
2. Background Art
Recently, various electronic apparatuses have been miniaturized and lightened in weight. The number of electronic apparatuses operated by selecting a predetermined function by moving a cursor displayed on a screen have been increased. A conventional input device corresponding to the operation form of the various electronic apparatuses is described hereinafter with reference to the drawings.
FIG. 9 is a conceptual diagram of a conventional input device. In FIG. 9, element unit 10 of the conventional input device includes circular arc resistive layer 1 and a circular-ring-like conductive layer 3 facing circular arc resistive layer 1 at a predetermined distance. Each of ends 1A and 1B of circular arc resistive layer 1 and conductive layer 3 are coupled to control unit 5. Circular arc resistive layer 1, conductive layer 3, and drawn parts from them are formed on resin films that are faced to each other, but are not shown.
As shown in a sectional view of FIG. 10 and an exploded perspective view of FIG. 11, operation body 15 having a spherical lower end used as an operation surface is disposed tiltably on element unit 10. Coil spring 17 is disposed in case 19 in order to support operation body 15 at a neutral position when operation body 15 is not operated.
Next, an operation of the conventional input device having the above-mentioned structure is described hereinafter. The conventional input device is operated by tilting operation body 15. In other words, the upper film is partially deflected with a pressing force from its outside using operation body 15, thereby providing a state where circular arc resistive layer 1 and conductive layer 3 partially come into contact with each other correspondingly to the deflected part. A predetermined voltage is placed between ends 1A and 1B of circular arc resistive layer 1 under control of control unit 5. The electric potential at the contact position is therefore input into control unit 5 through the drawn part from conductive layer 3. Control unit 5 specifies the operation position in response to a partial voltage ratio based on the input, and moves a cursor in response to the information.
Conventional art information related to the present invention is disclosed by Japanese Patent Unexamined Publication No. H11-232027, for example.
The structure of the conventional input device including its control method and its detection method of an operation position can be simplified, and especially element unit 10 can be thinned advantageously. However, the conventional input device has the following problem: when operation body 15 is tilted in an angle direction between ends 1A and 1B of circular arc resistive layer 1, ends 1A and 1B simultaneously come into contact with conductive layer 3 to provide a substantial short-circuit state. In this state, the quantity of flowing current increases to hasten the battery consumption, the output of the partial voltage ratio is the same as the output at the diagonal position to disable determination of the operation position, disadvantageously.
The conventional input device is used for only four-way operation or the like in an attached state to an apparatus. However, input devices have been demanded to have high resolution with recent enhancement in function of the apparatus.